The present invention relates to deep well sampling when drilling offshore for oil or gas and also for extracting production thereof. The invention includes a sampling device immersed into a drilled hole and which, at certain depths, takes samples of liquid and gas. When drilling for and production of hydrocarbons, it is important to take samples in the drill hole in order to detect the presence of gas and liquid traces. This is done by immersing a deep well sampler device into the drill hole. A container, in the sampling device, collects samples of what may be gas or liquid and is hoisted to a surface vessel. Such samples then are emptied into a transport container for laboratory analysis where the different characterizations of the substances in the samples are determined.
There exist known sampling devices described in U.S. Pat. No. 4,583,595 where a collecting sampler container for gas and liquid in a drill hole includes a piston device in order to separate physically the sample from substances which will blur the laboratory results. Such a substance may be a counter pressure substance used to regulate the collecting container level. During sampling the counter pressure substance is pressed out of the collecting container. The gas/liquid sample will, at the same time as the counter pressure substance is pressed out of the container, enter the container on the other side of the piston. An alternative to such container and piston is to furnish the sampling device with a compressible lead pipe as described in Norwegian patent application No 895,139. However, this sampler device comprises a pipe formed as a cylinder with two chambers separated by a compressible lead pipe. In addition, such device has a cylinder formed outer pipe which has therein a unit which forms a gastight collecting chamber for the gas/liquid sample and a chamber for the counter pressure substance. The chamber for the counter pressure substance is formed when the lead pipe is compressed and is pressing against the inner side of the U-shaped member. When filling the chamber the gas/liquid sample will move to the other side of the lead pipe and press this outwards. The volume of the chamber for the counter pressure substance will thus be reduced by the same amount as the increase in the sample chamber.